The present invention relates generally to a temperature pressure relief device (TPRD) for a high pressure storage vessel and more particularly to an integrated pressure sensor TPRD for fuel storage systems.
Electrochemical conversion cells, commonly referred to as fuel cells, produce electrical energy by processing reactants, for example, through the oxidation and reduction of hydrogen and oxygen. Hydrogen is a very attractive fuel because it is clean and can be used to produce electricity efficiently in a fuel cell. The automotive industry has expended significant resources in the development of hydrogen fuel cells as a source of power for vehicles. Vehicles powered by hydrogen fuel cells would be more efficient and generate fewer emissions than today's vehicles employing internal combustion engines.
In a typical fuel cell system, hydrogen or a hydrogen-rich gas is supplied as a reactant to the anode side of a fuel cell while oxygen (such as in the form of atmospheric oxygen) is supplied as a reactant to the cathode side of the fuel cell. One form of fuel cell, called the proton exchange membrane (PEM) fuel cell, has shown particular promise for vehicular and related mobile applications. The electrolyte layer of a PEM fuel cell is in the form of a solid proton-transmissive membrane (such as a perfluorosulfonic acid membrane, a commercial example of which is Nafion™). The presence of an anode separated from a cathode by an electrolyte layer forms a single PEM fuel cell; many such single cells can be combined to form a fuel cell stack, increasing the power output thereof. Multiple stacks can be coupled together to further increase power output.
The hydrogen for the fuel cell is commonly stored in a lightweight, high-pressure vessel resistant to puncture. These high-pressure vessels generally include a TPRD. The TPRD is in fluid communication with the interior of the vessel and is configured to vent the vessel gas when activated. Activation of the TPRD may occur in response to an emergency, for example, in the case of a fire. Activation of the TPRD allows the vessel gas to be released from the system. A typical high-pressure vessel TPRD includes a single-use activation mechanism, for example a liquid-filled bulb with an air bubble. The air bubble expands when heated and bursts the liquid-filled bulb upon reaching a specified temperature. A release piston, held in place by the intact bulb, is released when the liquid-filled bulb bursts, opening the gas release valve. The gas then escapes through the relief valve to avoid overpressure conditions due to high temperatures and related damage to the system.
In some cases, the release piston may become stuck due to mechanical blocking, for example corrosion or by other mechanical impacts between the piston and housing, during the TPRD lifetime. When this happens, the release piston will not move, even upon bursting of the liquid-filled bulb, and the vessel gas cannot be vented. Currently, there is no way to monitor the TPRD for mechanical blocking and related lack of release piston moveability.